Conventional fuel rails for fuel-injected internal combustion engines comprise sockets which are spaced apart along the fuel rail's length and into which the fuel injectors are inserted. The fuel injectors are retained in fluid-tight relation to the fuel rail by suitable sealing and retention means. The typical fuel injector has an elongated shape and is customarily arranged on the fuel rail such that the long dimension of the injector is transverse to the long dimension of the fuel rail. As a consequence of this arrangement, the envelope that is occupied by the fuel rail assembly in the engine compartment of an automotive vehicle will have an extent transverse to the fuel rail that is determined by the long dimension of the fuel injector. Accordingly, a reduction in the extent to which a fuel injector projects transversely of the fuel rail will be beneficial in reducing the envelope occupied by the fuel rail assembly, and this benefit will accrue to the advantage of automotive vehicle designers insofar as styling and packaging considerations are concerned.
One of the several aspects of the present invention relates to a fuel rail that contains a novel fuel injector configuration which allows for certain reductions in the size of the envelope that is occupied by the fuel rail assembly on an internal combustion engine, particularly reductions in the extent to which the fuel injectors project transversely of the fuel rail. More specifically, the fuel rail may comprise a circular cylindrical-walled tube within which the fuel injectors are essentially entirely disposed so that the transverse dimension of the fuel rail assembly at the location of a fuel injector is essentially that of the O.D. of the tube. The fuel injectors are mounted on a carrier to form a sub-assembly that is assembled into the tube by endwise insertion. The electrical leads for the fuel injectors run along the carrier to a receptacle that is at one lengthwise end of the completed fuel rail assembly. The injectors' tip ends from which liquid fuel is injected are seated in a sealed manner in holes in the sidewall of the tube.
The fuel injectors themselves are unique. Rather than having a solenoid, an armature, a needle, and a seat coaxially arranged along the length of the fuel injector, as in conventional fuel injectors, the fuel injector of the present invention has a magnetic circuit that encircles a spherical valve element. This sphere is resiliently urged by a cantilever spring blade toward closure of a hole that is circumscribed by a frusto-conical seat. The sphere-encircling magnetic circuit may be considered to comprise four sides. The armature and the solenoid are disposed at two opposite sides. The stator has a U-shape whose base passes through the solenoid and whose legs form the remaining two sides. The armature is a bar of magnetically permeable material whose midpoint acts on the sphere. When the solenoid is not energized, working gaps exist between the ends of the bar and the distal ends of the stator's legs, and when the solenoid is energized, the magnetic flux attracts the bar to reduce these working gaps. As a result, the bar pushes the sphere out of concentricity with the seat to cause the hole to open and pass for injection from the injector's tip end the pressurized liquid fuel that has been supplied to the injector via the interior of the fuel rail tube. When the solenoid is de-energized, the cantilever spring pushes the sphere back to concentricity with the seat, and the resultant hole closure terminates the injection. The fuel injector of the invention is well-suited for miniaturization to fit within a fuel rail and is an efficient and economical use of parts and materials.
Other inventive features relating to the fuel injectors involve control means for attenuating undesirable sphere bounce, and swirl-imparting means for imparting a swirl component to the injected fuel so that a conical-shaped injection spray may be produced.
Further features, advantages, and benefits of the invention, along with those already mentioned, will be seen in the ensuing description and claims, which are accompanied by drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.